ULTRASHORT TIME ECHO MRI SEQUENCE TO QUANTIFY VERTEBRAL BONE MORPHOLOGY IN YOUNG ADULTS

While MRI is the modality of choice for soft tissue imaging, its ability to visualize bone structures remains limited. In contrast, CT provides superior bone imaging but involves ionizing radiation, making it suboptimal for longitudinal studies in pediatric populations. This study investigates the feasibility of using Ultrashort Echo Time (UTE) MRI sequences to visualize vertebral bone anatomy and support reliable morphometric assessments over time. Three adolescent volunteers (mean age: 15 ± 1 years) underwent MRI scans including two UTE sequences of the thoracic and lumbar spine, acquired at two time points within a single imaging session. Registration between time points was evaluated using the Dice similarity coefficient and surface distance analysis, considering both 95th and 99th percentile thresholds were calculated. The segmentation achieved high repeatability with an average Dice coefficient of 0.92 ± 0.02. Mean surface distances between time points were 0.44 ± 0.08 mm at the 95th percentile and 0.50 ± 0.14 mm at the 99th percentile. Region-specific results showed slightly better agreement in the lumbar region (Dice: 0.94 ± 0.02) compared to the thoracic spine (Dice: 0.92 ± 0.02). UTE MRI provides enhanced bone contrast and enables accurate, repeatable vertebral segmentation. The observed surface distances fall below the expected yearly vertebral growth in healthy children (0.8-1.2 mm/year), indicating that UTE-based segmentation is sufficiently precise for longitudinal assessment of vertebral development without the risks associated with radiation exposure.